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Shekar R.I.,Defence Bio engineering and Electro Medical Laboratory | Rao P.M.D.,Central Silk Technological Research Institute | Padaki V.C.,Defence Bio engineering and Electro Medical Laboratory | Kim N.H.,Chonbuk National University | Lee J.H.,Chonbuk National University
Advanced Materials Research

The extruded poly ether ether ketone (PEEK) and glass fibre were used to obtain the co-woven hybrid fibre fabrics and converted into composites using compression moulding technique. The effect of shear stress and shear rate on the shear viscosity of PEEK was investigated to optimise the process conditions for converting hybrid fabrics into composites. The mechanical properties such as flexural strength and inter laminar shear strength (ILSS) as a function of number of layers of fabric have been evaluated. Low velocity (2.1 m/s) repeated drop weight impact tests were carried out on the fabricated composites at 5 and 10 J incident energy. Dielectric properties as a function of temperature and frequency have been carried out. Flammability behaviour of composites has been carried out using cone calorimeter. The data generated shows that glass-PEEK based composites are excellent potential materials for advanced structural composites. © (2010) Trans Tech Publications. Source

Shekar R.I.,Defence Bio engineering and Electro Medical Laboratory | Kotresh T.M.,Defence Bio engineering and Electro Medical Laboratory | Prasad A.S.K.,Defence Bio engineering and Electro Medical Laboratory | Rao P.M.D.,Central Silk Technological Research Institute | Kumar M.N.S.,National University of Malaysia
Journal of Applied Polymer Science

Poly ether ether ketone (PEEK) polymer was extruded into filaments and cowoven into unidirectional hybrid fabric with glass as reinforcement fiber. The hybrid fabrics were then converted into laminates and their properties with special reference to crystallization behavior has been studied. The composite laminates have been evaluated for mechanical properties, such as tensile strength, interlaminar shear strength (ILSS), and flexural strength. The thermal behavior of the composite laminates were analyzed using differential scanning calorimeter, thermogravimetric analyzer, dynamic mechanical analyzer (DMA), and thermomechanical analyzer (TMA). The exposure of the fabricated composite laminates to high temperature (400 and 500°C) using radiant heat source resulted in an improvement in the crystallanity. The morphological behavior and PEEK resin distribution in the composite laminates were confirmed using scanning electron microscope (SEM) and nondestructive testing (NDT). Although DMA results showed a loss in modulus above glass transition temperature (Tg), a fair retention in properties was noticed up to 300°C. The ability of the composite laminates to undergo positive thermal expansion as confirmed through TMA suggests the potential application of glass- PEEK composites in aerospace sector. © 2010 Wiley Periodicals, Inc. Source

Shekar I.R.,Defence Bio engineering and Electro Medical Laboratory | Kotresh T.M.,Defence Bio engineering and Electro Medical Laboratory | Prasad A.S.,Defence Bio engineering and Electro Medical Laboratory | Damodhara Rao P.M.,Central Silk Technological Research Institute | And 2 more authors.
Journal of Industrial Textiles

This article gives an insight into the design considerations that have been considered to design a technical hybrid fabric structure for Radome application. An attempt has been made to study empirical relationship between various structural parameters that have a major influence on the final composite properties. The hybrid fabric structures woven out of E-glass (warp) and PEEK (weft) and E-glass (warp) and polyester (weft) have been designed based on mathematical approach and expressed in terms of geometrical parameters in order to have a complete geometric specification of the fabric. An effort has also been made to understand in a comprehensive manner the interrelationships between geometrical properties of yarns and fabrics and their influence on processing of composites and their performance. The study shows that impregnation of resin within the fiber network is primarily responsible for intimate fiber-fiber contact that contributes for the final properties in the composite and provides a good interface area in the composite. The effect of short processing cycle is also attempted keeping in view the techno-economic aspects and it is found that long process cycle with stand in time at major transition temperatures gives useful properties compared to short process cycle. Glass-polyester-based composites are also prepared and studied to have relative performance of glass-PEEK composites. © SAGE Publications 2011. Source

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